1. Technical Field
The present invention relates to a method and system for signal processing in general, and in particular to a method and system for processing pulsed signals. Still more particularly, the present invention relates to a method and system for improving process shadow time within a pulsed signal processing system.
2. Description of the Prior Art
In military defense, once a new weapon is developed, typically another weapon will be invented to counteract the first weapon. For example, since the introduction of radar in World War II, many different strategies have been developed to interfere with and to defeat radar effectiveness. These strategies are often referred to as electronic countermeasures (ECMs). Some successfully developed ECMs that have been popularized over the years to inhibit radar effectiveness include, inter alia, chaffs and jammers.
But with the improvement of radar technology and the increasing complexity of the electronic signal environment, not only are there more radars in operations today, the radar signals themselves are also more sophisticated than their predecessors. Not surprisingly, more sophisticated ECMs have been developed as a result. For example, an electronic warfare receiver, commonly referred to as an intercept receiver, has been developed to detect the existence of radar signals from a hostile source. Even so, because detailed information about the radar system from a hostile source is seldom available, it is almost impossible to design an intercept receiver as effective as the radar receiver in the radar system. Fortunately, due to the fact that the distance travelled by the radar signal from the radar system source to the intercept receiver is half the distance from the same radar system source to the radar receiver, the signal strength at the input of the intercept receiver is much stronger than the signal strength at the radar receiver. Therefore, if an intercept receiver is properly designed, the intercept receiver can effectively detect the radar signal from a hostile source.
Generally speaking, an intercept receiver is a pulsed signal processing system. A pulsed signal processing system processes each radar signal pulse as the radar signal pulse is being detected. The timeframe after a radar signal pulse detection in which the pulsed signal processing system cannot (or is not ready) to detect another radar signal pulse is referred to as "shadow time." One main drawback of prior art pulsed signal processing systems is that these pulsed signal processing systems must wait for a long period of time for the radar signal level to decay below the system threshold level in order to process a subsequent pulse, even though the radar signal may have already ended. In other words, these pulsed signal processing systems have a very long process shadow time. With a very long process shadow time, any of the following problems can occur: (1) system processing throughput is limited by the incapability to handle dense pulsed signal environments; (2) pulse signals that occur within the process shadow time of a previous pulse signal will go undetected; and (3) pulse signal widths will be measured inaccurately when portions of the pulse signal fall within the process shadow time of a previous pulse signal. Consequently, it would be desirable to provide a method to improve process shadow time within a pulsed signal processing system.